Correlation between ANA determinations on tissue substrate, WiL-2 cell substrate, and precipitin antibody by double diffusion.

Four hundred fifty-five sera from patients with various connective tissue diseases were screened for the presence of fluorescent antinuclear antibodies (ANA) on two different substrates-mouse kidney sections and WiL-2 cell smears-and precipitin antibodies by using WiL-2 cell extracts as an antigenic source. The antigen for the precipitin was prepared as for extractable nuclear antigen tests. Of 258 sera from systemic lupus erythematosus cases, 73% were positive for ANA on mouse kidney sections, 98% on Wil-2 cell smears, and 47% by precipitin tests. However, 33 sera which were ANA negative on mouse kidney sections were positive on WiL-2 cell smears and also positive for precipitin antibodies. WiL-2 cells used as ANA substrates increased the frequency of ANA in connective tissue diseases, and there was a strong correlation between the WiL-2 cell ANA and the presence of precipitin antibodies. Twenty-four of these 33 sera had anti-SSA/Ro antibody. Some sera containing anti-SSB/La or anti-nRNP antibodies were ANA negative on mouse kidney sections, but all were positive on WiL-2 cells.